Durston and colleagues also found evidence that compared to non-ADHD, ADHD children also activate a more diffuse network of posterior and dorsolateral prefrontal cortex regions to subserve successful response inhibition (Durston et al., 2003). Increasing age also significantly alters the pattern of activity seen on Go/No-Go tasks for healthy, non-ADHD persons in these brain regions. Children activate more volume of prefrontal cortex compared to adults (Casey et al., 1997). There also is evidence that healthy adults and teenagers use different neural networks to achieve comparable response inhibition task performance (Rubia et al., 2000). Healthy adults show modulation of ventral prefrontal activity depending on task difficulty, whereas children appear to maximally activate these areas generally (Durston et al., 2002). In a sample of ADHD participants ages 8 to 20, age was found to correlate positively with left inferior frontal cortex, and correlate negatively with hemodynamic activity in left dorsolateral prefrontal cortex (Tamm et al., 2002). In other words, there was increasing use of cortex known to be a primary substrate of response inhibition, while reliance on cortex that is a primary substrate of working memory and other "on-line" cognitive processes decreased with age. These differences suggest that age is an important variable in understanding response inhibition neural activity in both ADHD and non-ADHD persons.